This research program has been directed to determine the fundamental biochemical processes that are involved in the regulation of differential gene transcription during mammalian spermatogenesis. Particular emphasis will be placed on characterizing the chromosomal proteins, histone and non-histone, which are present in isolated spermatogonia, pachytene primary spermatocytes, round spermatids, condensing spermatids and mature spermatozoa. Concurrent studies will be undertaken to determine the temporal pattern of RNA synthesis during spermatogenesis in an effort to correlate changes in the level of gene transcription with the synthesis modification or diminution of specific proteins in chromatin that is recovered from the respective cell types. SPECIFIC OBJECTIVES INCLUDE: (1) Determine the temporal pattern of histone synthesis during spermatogenesis with emphasis on defining the pre-meiotic cell type responsible for the synthesis of the testis-specific histone 1 and confirm that histone 2S is synthesized during meiotic prophase, (2) isolate and characterize histone 2S, (3) characterize the non-histone proteins which occur in the respective cell type by SDS-polyacrylamide gel electrophoresis, (4) determine when the non-histone proteins of mature spermatozoa are synthesized during spermatogenesis, (5) examine the temporal pattern of RNA synthesis and storage in meiotic and post-segregational spermatogenic cells, and, (6) isolate and characterize the chromatoid body which is present in round spermatids. BIBLIOGRAPHIC REFERENCES: Bellve, A. R., Bhatnager, Y. M. and Romrell, L. J. (1975) Histone synthesis and fate during spermatogenesis. J. Cell Biol. 67:26. Bellve, A. R., Romrell, L. J., and Fawcett, D. W. (1976) Separation of mouse spermatogenic cells by sediment velocity: A morphological characterization. Dev. Biol. 49: (In press).